You can find Hotpoint fault codes here http://www.hotpointservice.co.uk/hs/pages/content.do?keys=FAQ
F04 - Pressure switch jammed on empty
However it can also be a blockage of the pipe to the pressure switch.
On my machine ( a WD640 ) this was caused by the trap/filter in the hose to the pump being clogged.
What idiot designs a machine that you have to turn on its side and remove a hose in order to clean the filter?
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